If your friend (or you) click on this link: If LW Will Not Connect (click on the blue link)

you'll find detailed instructions for finding the file on XP & a couple of links to help on Vista. He'll need to make sure that he's showing hidden files & folders on his computer - the file lives within a folder that's hidden by deault.

For 5.0.11, he should only need to delete the file rather than replace it